In July, Megan Lawless married Jasper Jasperse, whom she met as a random opponent while playing the Scrabble-like game Words With Friends on her smartphone in 2009. At that time, Lawless, now 32, lived in Chicago while Jasperse, now 31, hailed from Amsterdam.

The couple gradually got to know each other through the game's chat feature, Lawless tells Fast Company.

Like many Words With Friends players, Lawless has never considered herself a gamer, but she said she loves the word game because "it is about interacting with people .... Like most people, I have friends and family all over the world, and this game allows me to play and chat with those I rarely get a chance to talk to, but I know they are going to play their turn. And it's fun."

Words With Friends has 14.9 million monthly active users and 6.7 million daily users, both on smartphones and on Facebook, according to AppData. The game makes money through ads, an ad-free paid version, and recently through in-game purchase options. And the mainstream popularity of the title helped build buzz for Zynga's$1 billion IPO.

Words With Friends was released in July 2009 by Newtoy, a small studio run by two brothers, Paul and David Bettner, in McKinney, Texas. Newtoy was acquired by Zynga in late 2010 and rebranded as the division Zynga With Friends. The Bettners released Chess With Friends in 2008, Hanging With Friends in 2011, and Scramble With Friends in 2012.

Paul Bettner, now vice president and general manager of Zynga With Friends, tells Fast Company he and his brother had tried to redesign the classic board game from a blank slate, by reworking the distribution of letters and point values. They introduced some randomness by configuring for bigger point combos, he says, which they thought would make the game appeal more to casual players. But they also spent a lot of time working on the feel, on making sure users felt like they were "reaching through the glass into this little world just below." (It's what makes competitors feel clunky by comparison.) "The goal was something lightweight and casual, something anyone can pick up immediately, without an instruction manual. Users have to start having fun in the first two seconds," Bettner says.

And Words With Friends' secret sauce, to which newlyweds Lawless and Jasperse might attest, is the social element that was baked into the game from early on. The Bettners were inspired by the tradition of playing chess through the mail, and they wanted to replicate the feel of sitting around the table with friends playing a board game, Bettner says.

"I think the most fundamental part of our success is the social connection, which sometimes I call obligation or guilt—the connection that forms in the game when people commit to each other to play," Bettner says.

Facebook, he adds, "helps our audience find their friends in the game." He says the best thing about the ability to play the game within Facebook itself is that Words With Friends "follows you around, whether you are on a computer, or on the go on your cell phone."

Words With Friends wasn't the first Scrabble-like game on the Internet. In 2005, two other brothers, Rajat and Jayant Agarwalla of Calcutta, India, launched Scrabulous online. In 2007, they launched a Facebook app of that game, which quickly went viral.

In 2008, the owners of Scrabble sued the Agarwallas for copyright infringement, and Scrabulous was shut down. Not long after that the Agarwallas rereleased the game under the name Lexulous. But the damage had been done, according to Scott Steinberg, a mobile games analyst and head of strategic consulting firm TechSavvy. "The lawsuits derailed them at a crucial growth phase," Steinberg says.

"Words With Friends came at the right moment for mobile games," Steinberg adds. "It spans different ages and backgrounds, and with the asynchronous play, people might spend quite a bit of time with it, spread out in chunks through the day."

The owners of Scrabble (Hasbro in the U.S. and Canada, Mattel elsewhere) have mobile games that compete with Words With Friends, but they haven't been as popular. "Some of those titles are polished efforts, but they have failed to recognize that you need to provide accessibility and convenience," Steinberg says, adding that Zynga's line has always kept the focus on "friends," with simple menus and no option to play a computer, which complicates things.

Hasbro did not return requests for comment on this story. Jayant Agarwalla of Lexulous told Fast Company via email, "When we first saw Words With Friends, we realized they had done an amazing job.

"They did three very important things (that we are trying to do now in our relaunch): They removed unnecessary and less-used features, such as picking opponents, setting up challenge mode games, selecting a dictionary, etc. Next, they had a smooth, top-notch interface that made it a breeze starting games and ensuring the learning curve was small. Finally, they had all the tools required for a viral effect, i.e., multiple sharing options, ability to start games with people on the contact list, etc. All combined, it was a winning formula."

The Agarwallas expect to release a streamlined version of Lexulous in the next few weeks. It remains to be seen if the changes will be enough to eat at Words With Friend's marketshare. For now, Zynga's title seems to have the right combination of nostalgia for the game you played with your grandma and an interface that makes it well suited to the smartphone environment.

For her part, Megan Lawless said she has so many friends playing Words With Friends these days that she doesn't have time to play random opponents, although her husband still does. "As long as he doesn't propose marriage I'm fine with it," she laughed.